Fate of the fetus

As politicians debate, science reveals more and more about what happens during pregnancy

Dr. Victor Han, professor and Canada research chair in maternal and fetal health at Western University in London.

Dr. William Smalling first saw the baby on day two of life.

Amillia Taylor, one of the world’s smallest surviving preemies, weighed just 283 grams and measured 24 centimetres — under 10 inches — with skin so fragile and translucent her blood vessels could be seen beneath.

“I was shocked that something so small could survive,” Smalling, one of Amillia’s primary physicians, remembers thinking that day as he stood in his hospital’s neonatal intensive care unit.

“Not only survive, but also be so stable.”

Born after just 21 weeks and six days’ gestation in a South Florida hospital in 2006, Amillia arrived in the world by emergency caesarean section, pushing the boundaries of what is known as the “threshold of viability” — the stage and age at which a fetus would have a reasonable chance of survival outside its mother’s womb without severe brain damage.

According to Canadian reproductive biology expert Dr. Roger Pierson, “Nobody really knows where that line is anymore.”

As medical advances allow doctors to increasingly save babies born months too soon — those who would never have survived even a generation ago — the debate over fetal viability has been reignited.

In Canada, it’s happening against the backdrop of a renewed political battle over abortion. This past week, a Conservative MP accused his party of muzzling him when he tried to raise abortion-related issues. Earlier this year, three Conservative MPs asked the RCMP to investigate late-term abortions as possible homicides. Last year, a Conservative MP pushed unsuccessfully for a special committee to study whether medical evidence supports the idea that a child is a human being before the moment of birth. Whatever direction the political debate takes, it has raised anew the broad issue of fetal viability. And the questions are only getting bigger — and more complex.

Advances in fetal imaging have opened a once-unimagined portal into the world of the unborn, changing what we can see, and what medicine can do. Four-dimensional ultrasound — 3D images that move in real-time — is capturing thumb-sucking, yawning and facial expressions such as crying and scowling in the fetus, as early as 22 or 23 weeks’ gestation. It’s difficult to say what’s a true, purposeful movement, and what is merely reflex.

Until now, it was thought the brain was neurologically immature until about 25 or 26 weeks.

“All those thoughts are now changing,” says Smalling, a neonatologist at Baptist Children’s Hospital in Miami, Fla.

Imaging now allows doctors to not only diagnose devastating defects of the brain and spinal cord, such as spina bifida, sooner, but also fix some of them in the womb.

The technology is moving so rapidly, Pierson envisions the day pregnant women will walk into phone booth-like scanners, “and you will see everything, inside and out, from a surface level down to a cell level.

“The question is, if we detect an anomaly — and an anomaly is defined as something ‘abnormal’ — what do we do about it?” says Pierson, a professor of gynecology and reproductive sciences at the University of Saskatchewan in Saskatoon.

After nearly three decades of work in this field, Pierson still finds the journey from conception to birth, the exquisitely choreographed building of a human, “a bit of a miracle.”

At three weeks gestation, the brain, spinal cord, gastrointestinal tract and heart begin to develop. At week five, the fetus is about the size of a pumpkin seed. By week seven, all essential organs have begun to form.

By the end of the second trimester, the fetus can hear. But this doesn’t show what the fetus may experience.

“We can tell you how the brain develops; we can tell you when the folds that are associated with higher order thoughts are formed in utero,” says Pierson. “But we can’t tell you what an embryo or a fetus thinks, or what it feels.

“And I would rank this as one of the most difficult areas in all of medicine, because we don’t know, and because it’s full of emotion.”

After sperm penetrates egg, a rapidly dividing ball of cells called a blastocyst buries itself deep in the lining of the uterine wall.

The organs begin to form about three weeks after fertilization. The neural tube, the area that will form the brain and spinal cord, begins to develop 22 days post-conception. By week five, the heart, although far from fully formed, begins to beat.

“Very early in the pregnancy, we can see a heart beat at six weeks very clearly on ultrasound,” says Dr. Andree Gruslin, interim chief of the department of obstetrics and gynecology at The Ottawa Hospital.

At 11 weeks on ultrasound, “I can see the head, I can see the limbs, the umbilical cord, the stomach, the bladder, very clearly.”

The first trimester is critical. At 10 weeks, several abnormalities that can occur — if they do — develop now. “Smoking (in pregnancy), alcohol use, drug use — all those things are critical throughout development but in particular the first trimester,” Smalling says.

By 22 weeks, the middle of the second trimester, the heart, lungs and kidneys have developed into a more human-like form. At a gestational age of five months, the brain is mostly smooth on the surface. By seven months, it has almost doubled in size. “In all mammals, the brain develops preferentially over the other systems,” Pierson says. “But it doesn’t answer: what’s going on inside? For all the observations that we make, we fundamentally still don’t quite know.”

Among the most controversial questions: When does the fetus have the capacity to feel pain?

In the U.S., several states have outlawed abortions after 20 weeks gestation, based on the assumption that fetuses feel pain at that point.

However, in a report released in 2010 by the Royal College of Obstetricians and Gynaecologists in the United Kingdom, experts who reviewed international studies published since the 1990s concluded that a fetus couldn’t feel pain before 24 weeks because the neural connections in the brain aren’t fully formed.

The group also said that, because of the chemical environment of the womb, a fetus never experiences a true state of wakefulness. Rather it’s kept in a “continuous, sleep-like consciousness or sedation.”

But the fetal brain is constantly in evolution, said Gruslin, of The Ottawa Hospital. “Do they really feel pain and when does that happen? I don’t know that we know for sure,” she said.

During an amniocentesis, in which an ultrasound-guided needle is passed through the abdomen and into the uterus to detect Down syndrome and other chromosomal abnormalities, “if the baby happens to feel the catheter that’s inside, sometimes you’ll see the arm move away,” Gruslin said.

“In late gestation, they feel something. Is it pain? I don’t know.”

Uncertainty also exists around the “borderlands” of viability outside the womb.

According to the Canadian Medical Association’s policy on induced abortion, viability may be possible if the fetus weighs more than 500 grams or is past 20 weeks’ gestation.

However, in a position statement on managing extremely preterm births published last year, the Canadian Paediatric Society’s fetus and newborn committee states that “survival is uncommon” for infants born below or at 22 weeks of completed gestation. The statement recommends a “non-interventional approach” for these babies, after discussion with the parents, with a focus instead on “comfort care.” That means the baby would not be actively resuscitated, intubated, ventilated or given cardiac compressions — in essence, no heroic measures to keep the baby alive.

“I think, as neonatologists, that we more or less believe that 23 weeks is probably the limit of viability,” says Dr. Victor Han, Canada Research Chair in fetal and maternal health and chair of the division of neonatal-perinatal medicine at Western University in London, Ont.

The grey area is between 23 and 25 weeks. “It all depends on the parents and what the expectations are of a baby that has been delivered so prematurely,” Han says. “You will have moms and dads who say we would like to have a baby, irrespective of what the outcome will be — whether the baby is going to have cerebral palsy or breathing problems or any long-term problems that babies can have when born prematurely.”

The other extreme, he says, are parents “who say, ‘we want a perfect baby … we cannot accept these potential complications. We don’t want any resuscitative efforts. We’re OK with just compassionate care.’”

Sonja Barton-Taylor, Amillia’s mother, knew almost to the day how far along she was in her pregnancy when she went into preterm labour, because Amillia was conceived through in vitro fertilization, or IVF. When the doctors told her an ultrasound scan was showing that Amillia was 23 weeks, “I let the doctors believe what they wanted to believe” fearing they would not try to save the baby if they knew she was under 22 weeks’ gestation.

Today, Amillia is in kindergarten. She’s small for her age and has some developmental delays. She also has trouble with her feet: one is turned in slightly, and she will need surgery to correct it. But, in every other way, “she’s a normal kindergartner,” her mother says. “She runs, she plays, she does things she’s not supposed to do.” Her favourite food is sausage pancakes.

Sonja Barton-Taylor once told the British newspaper The Daily Mail that, when Amillia was born, her skin was so transparent Sonja could watch her lungs expand and contract.

Amillia’s hand was the size of her thumbnail, she told the paper, Amillia’s leg the length of her little finger.

Saving babies at 22 weeks’ gestation may be as low we can go, for now. But the technology and knowledge is expanding at a rate never before seen in our species, Pierson says.

“And I doubt very seriously whether that limitation will last very long.”

Key changes during embryonic and fetal development

Week 3

Brain, spinal cord, heart, gastrointestinal tract start to develop.

Weeks 4-6

Arm and leg buds become visible.

The brain develops into five areas; the eyes and ears begin to form.

The heart continues to develop and now beats at a regular rhythm.

Nose, mouth and ears begin to form.

Weeks 7-8

Elbows and toes are visible.

By the end of the second month, all major organs and body systems have begun to form; in the brain, nerve cells are branching out to connect with one another.

Weeks 9-12

Eyelids close and won’t reopen until about the 28th week.

The hands are more developed than the feet and the arms are longer than the legs.

Weeks 13-16

More muscle tissue and bones have developed.

The arms and legs can flex.

The mouth makes sucking motions.

Weeks 17-19

The fetus can hear sounds; the mother may feel fluttering in the lower abdomen.

Weeks 20-23

Fetal heartbeat can be heard with a stethoscope.

Bone marrow begins to make blood cells.

The lower airways of lungs develop but still do not produce surfactant, a substance that helps inflate the air spaces in the lungs.

Weeks 24-28

Air sacs form in lungs; the lungs start to produce surfactant.

Rapid brain development occurs.

The fetus kicks and stretches and can make gasping motions.

Eyes can open and close and sense changes in light.

Weeks 29-36

Rapid increase in the amount of body fat.

Rhythmic breathing movements occur.

Bones are fully developed but still soft and pliable.

Weeks 37-40

Fetus considered full term; the brain continues to develop until the time of delivery and in the first year of life after birth.

Sources: The American College of Obstetricians and Gynecologists; University of Maryland Medical Centre

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